RESUMO
La displasia dentinaria tipo I (DD-I) corresponde a una alteración dentinaria de heterogeneidad genética y penetrancia completa, en donde se presenta un defecto en el desarrollo de las raíces de los dientes tanto temporales como definitivos. Clínicamente se observan dientes con extrema movilidad junto con antecedentes de exfoliación prematura o espontánea. Los defectos estructurales de los tejidos dentarios, tales como DD-I; implican un desafío ya que son pocos los casos documentados en la literatura que hablan de esta condición. Además implican un tratamiento multidisciplinario y altamente invasivo. El objetivo de este artículo es presentar dos casos de DD-I, enfatizando en su tratamiento y características histopatológicas.
Dentin Dysplasia Type I (DD-I) consists of a pathological dentinary alteration with genetic heterogeneity that results in a defectuous development of dental roots both in primary and secondary dentition. Clinically we can appreciate teeth with extreme pathological mobility and premature or spontaneous exfoliation. Alterations within normal dental structure, such as DD-I imply a challenge for the common practitioner, because of the scarce number of case reports with in the scientific literature regarding this condition and also, because of the need for a highly invasive and multidisciplinary approach they require. The aim of this article is to present two DD-I cases, emphasizing on their treatment and histopathological features.
Assuntos
Humanos , Feminino , Adolescente , Adulto , Raiz Dentária/anatomia & histologia , Penetrância , Displasia da DentinaRESUMO
BACKGROUND: Retinoblastoma (Rb) most frequently presents as a unilateral sporadic disease up to 40% of cases, however, arise from a monoallelic germline pathogenic variant. Only 10% of the germline mutations are inherited, and high penetrance is seen in up to 90% of these cases. As an effort to optimize counseling and screening, mutations are classified according to inheritance patterns. However, RB1 spectrum is highly heterogeneous, and information for unaffected carriers remains scarce. MATERIALS AND METHODS: The Mexican family of a 5-month-old patient diagnosed with Rb was studied. The family consisted of five individuals (father, mother, and three siblings). Genetic testing using a next-generation sequencing assay targeting RB1 with oligonucleotide baits designed to capture its exons and 20 bases flanking intronic sequences was performed in every family member. Clinical history and a complete ophthalmological examination (best-corrected visual acuity, slit-lamp biomicroscopy, macular optical coherence tomography, fundus autofluorescence, optical coherence tomography angiography, and electrophysiological studies) were performed in members testing positive to RB1 mutation. RESULTS: The father and her five-month-old daughter tested positive for a non-synonymous RB1 mutation c.459del (p.Lys154Serfs*21). The girl presented with bilateral retinoblastoma, successfully treated with cryotherapy and intravenous chemotherapy. The father had no relevant findings on imaging studies or ophthalmologic evaluation. CONCLUSIONS: This report describes a rare case of a novel low-penetrance RB1 germline mutation. Long-term follow-up of the father will include periodic evaluation of the eyes and orbits, and surveillance for systemic sarcoma and secondary malignancies. Implications for unaffected individuals need to be further studied.
Assuntos
Neoplasias da Retina , Retinoblastoma , Análise Mutacional de DNA , Éxons , Feminino , Mutação em Linhagem Germinativa , Humanos , Lactente , Masculino , Mutação , Penetrância , Neoplasias da Retina/diagnóstico , Neoplasias da Retina/genética , Neoplasias da Retina/patologia , Retinoblastoma/diagnóstico , Retinoblastoma/genética , Retinoblastoma/patologia , Proteínas de Ligação a Retinoblastoma/genética , Ubiquitina-Proteína Ligases/genéticaRESUMO
Genetic predisposition accounts for nearly 10% of all melanoma cases and has been associated with a dozen moderate- to high-penetrance genes, including CDKN2A, CDK4, POT1 and BAP1. However, in most melanoma-prone families, the genetic etiology of cancer predisposition remains undetermined. The goal of this study was to identify rare genomic variants associated with cutaneous melanoma susceptibility in melanoma-prone families. Whole-exome sequencing was performed in 2 affected individuals of 5 melanoma-prone families negative for mutations in CDKN2A and CDK4, the major cutaneous melanoma risk genes. A total of 288 rare coding variants shared by the affected relatives of each family were identified, including 7 loss-of-function variants. By performing in silico analyses of gene function, biological pathways, and variant pathogenicity prediction, we underscored the putative role of several genes for melanoma risk, including previously described genes such as MYO7A and WRN, as well as new putative candidates, such as SERPINB4, HRNR, and NOP10. In conclusion, our data revealed rare germline variants in melanoma-prone families contributing with a novel set of potential candidate genes to be further investigated in future studies.
Assuntos
Predisposição Genética para Doença/genética , Melanoma/genética , Mutação/genética , Neoplasias Cutâneas/genética , Adolescente , Adulto , Idoso , Brasil , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Linhagem , Penetrância , Sequenciamento do Exoma/métodos , Melanoma Maligno CutâneoRESUMO
Li-Fraumeni syndrome (LFS) is an autosomal dominant cancer predisposition syndrome caused by pathogenic germline variants in the TP53 gene, characterized by a predisposition to the development of a broad spectrum of tumors at an early age. The core tumors related to LFS are bone and soft tissue sarcomas, premenopausal breast cancer, brain tumors, adrenocortical carcinomas (ACC), and leukemias. The revised Chompret criteria has been widely used to establish clinical suspicion and support TP53 germline variant testing and LFS diagnosis. Information on TP53 germline pathogenic variant (PV) prevalence when using Chompret criteria in South America and especially in Brazil is scarce. Therefore, the aim of this study was to characterize patients that fulfilled these specific criteria in southern Brazil, a region known for its high population frequency of a founder TP53 variant c.1010G>A (p.Arg337His), as known as R337H. TP53 germline testing of 191 cancer-affected and independent probands with LFS phenotype identified a heterozygous pathogenic/likely pathogenic variant in 26 (13.6%) probands, both in the DNA binding domain (group A) and in the oligomerization domain (group B) of the gene. Of the 26 carriers, 18 (69.23%) were R337H heterozygotes. Median age at diagnosis of the first tumor in groups A and B differed significantly in this cohort: 22 and 2 years, respectively (P = 0.009). The present study shows the clinical heterogeneity of LFS, highlights particularities of the R337H variant and underscores the need for larger collaborative studies to better define LFS prevalence, clinical spectrum and penetrance of different germline TP53 pathogenic variants.
Assuntos
Mutação em Linhagem Germinativa , Síndrome de Li-Fraumeni/patologia , Análise de Sequência de DNA/métodos , Proteína Supressora de Tumor p53/genética , Adolescente , Adulto , Brasil , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Síndrome de Li-Fraumeni/genética , Masculino , Pessoa de Meia-Idade , Penetrância , Fenótipo , Prevalência , Adulto JovemRESUMO
The TP53-R337H founder mutation exists at a high frequency throughout southern Brazil and represents one of the most common germline TP53 mutations reported to date. It was identified in pediatric adrenocortical tumors in families with a low incidence of cancer. The R337H mutation has since been found in association with early-onset breast cancers and Li-Fraumeni syndrome (LFS). To study this variability in tumor susceptibility, we generated a knockin mutant p53 mouse model (R334H). Endogenous murine p53-R334H protein was naturally expressed at high levels in multiple tissues and was functionally compromised in a tissue- and stress-specific manner. Mutant p53-R334H mice developed tumors with long latency and incomplete penetrance, consistent with many human carriers being at a low but elevated risk for cancer. These findings suggest the involvement of additional cooperating genetic alterations when TP53-R337H occurs in the context of LFS, which has important implications for genetic counseling and long-term clinical follow-up. SIGNIFICANCE: A p53-R334H knockin mouse serves as an important model for studying the most common inherited germline TP53 mutation (R337H) that is associated with variable tumor susceptibility.
Assuntos
Modelos Animais de Doenças , Células Germinativas/metabolismo , Mutação em Linhagem Germinativa , Síndrome de Li-Fraumeni/genética , Camundongos/genética , Mutação de Sentido Incorreto , Penetrância , Proteína Supressora de Tumor p53/genética , Animais , Brasil/epidemiologia , Células Cultivadas , Feminino , Fibroblastos/metabolismo , Técnicas de Introdução de Genes , Predisposição Genética para Doença , Síndrome de Li-Fraumeni/epidemiologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos TransgênicosRESUMO
Sodium voltage-gated channel α subunit 5 (SCN5A)-mutations may cause an array of arrhythmogenic syndromes most frequently as an autosomal dominant trait, with incomplete penetrance, variable expressivity and male predominance. In the present study, we retrospectively describe a group of Mexican patients with SCN5A-disease causing variants in whom the onset of symptoms occurred in the pediatric age range. The study included 17 patients with clinical diagnosis of primary electrical disease, at least one SCN5A pathogenic or likely pathogenic mutation and age of onset <18 years, and all available first- and second-degree relatives. Fifteen patients (88.2%) were male, and sixteen independent variants were found (twelve missense, three truncating and one complex inframe deletion/insertion). The frequency of compound heterozygosity was remarkably high (3/17, 17.6%), with early childhood onset and severe disease. Overall, 70.6% of pediatric patients presented with overlap syndrome, 11.8% with isolated sick sinus syndrome, 11.8% with isolated Brugada syndrome (BrS) and 5.9% with isolated type 3 long QT syndrome (LQTS). A total of 24/45 SCN5A mutation carriers were affected (overall penetrance 53.3%), and penetrance was higher in males (63.3%, 19 affected/30 mutation carriers) than in females (33.3%, 5 affected/15 carriers). In conclusion, pediatric patients with SCNA-disease causing variants presented mainly as overlap syndrome, with predominant loss-of-function phenotypes of sick sinus syndrome (SSS), progressive cardiac conduction disease (PCCD) and ventricular arrhythmias.
Assuntos
Canalopatias/genética , Coração/fisiologia , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Adolescente , Arritmias Cardíacas/genética , Síndrome de Brugada/genética , Doença do Sistema de Condução Cardíaco/genética , Criança , Pré-Escolar , Feminino , Heterozigoto , Humanos , Lactente , Síndrome do QT Longo/genética , Masculino , Mutação/genética , Penetrância , Fenótipo , Polimorfismo de Nucleotídeo Único/genética , Estudos Retrospectivos , Síndrome do Nó Sinusal/genéticaRESUMO
Relative frequency of hereditary ataxias remains unknown in many regions of Latin America. We described the relative frequency in spinocerebellar ataxias (SCA) due to (CAG)n and to (ATTCT)n expansions, as well as Friedreich ataxia (FRDA), among cases series of ataxic individuals from Peru. Among ataxic index cases from 104 families (38 of them with and 66 without autosomal dominant pattern of inheritance), we identified 22 SCA10, 8 SCA2, 3 SCA6, 2 SCA3, 2 SCA7, 1 SCA1, and 9 FRDA cases (or families). SCA10 was by far the most frequent one. Findings in SCA10 and FRDA families were of note. Affected genitors were not detected in 7 out of 22 SCA10 nuclear families; then overall maximal penetrance of SCA10 was estimated as 85%; in multiplex families, penetrance was 94%. Two out of nine FRDA cases carried only one allele with a GAA expansion. SCA10 was the most frequent hereditary ataxia in Peru. Our data suggested that ATTCT expansions at ATXN10 might not be fully penetrant and/or instability between generations might frequently cross the limits between non-penetrant and penetrant lengths. A unique distribution of inherited ataxias in Peru requires specific screening panels, considering SCA10 as first line of local diagnosis guidelines.